1. Field of the Invention
The present invention relates to a photoelectronic sensor system which is provided with a sensor section including a light emitting element emitting a light emission signal and a light receiving element receiving a reflection signal obtained by reflecting the light emission signal from the light emitting element by a body to be detected or a transmission signal obtained by transmitting the light emission signal through the body to be detected, where the reflection signal obtained by reflecting the light emission signal by the body to be detected or the transmission signal obtained by transmitting the light emission signal by the body to be detected is captured by the light receiving element so that presence/absence of the body to be detected is detected.
2. Description of the Related Art
Conventionally, in storage or management of articles, detecting presence/absence of the articles or a storage position thereof is important for managing the storage number of the articles or a storage place or a storage position thereof at the so-called cell production step such as a manufacturing step of the articles, a manufacturing step of products using these articles or an assembling step thereof, or an inspecting step or at a use time of these articles. Since management information about the storage number, the storage place, or the storage position is transmitted to a host system or an automated machine at the next step so that automation of a manufacturing line or an inspection line, or a step in storage and management can be realized, photoelectronic sensors or the like are used. For example, in production of glasses for liquid crystal, glass plates for a disk, printed boards, or semiconductor substrate wafers, photoelectronic sensors are used for detecting a residence site of a wafer cassette or articles on a storage shelf, or presence/absence of articles.
Alternatively, in storage and management of regular articles or regular apparatuses, photoelectronic sensors are used for detecting presence/absence of the articles or the apparatuses, or a storage position thereof.
For example, Patent Literature 1 describes a photoelectronic sensor where light emission signal is guided from a light emitting element to a light emitting window by an optical fiber for light emission, the light emission signal emitted from the light emitting window is guided to a light receiving element through an optical fiber for light reception as light reception signal, and presence of a wafer is detected based upon blocking of the light emission signal performed by a wafer which is a body to be detected. However in this case, using of the optical fiber intervening in the light emitting element or the light receiving element attenuates light emission signal or light reception signal due to taking-in or a transmission distance of the light from the light emitting element, which results in such a problem that light emission with high luminance or light reception with high luminance cannot be achieved efficiently. That is, such a problem is included that reflection at a light taking-in portion of an optical fiber or attenuation of light due to an optical fiber makes effective utilization of an optical signal difficult and blocks improvement of sensitivity of a photoelectronic sensor. There is a problem that it is necessary to perform luminance adjustment of each of a plurality of light emitting elements or perform light reception sensitivity adjustment of each of a plurality of light receiving elements, which requires time and labor for adjustment, and readjustment is required due to change of environment according to installation or disturbance, so that complicated adjusting work is required. When the photoelectronic sensors are generally used for detecting a plurality of bodied to be detected, a bundle of optical fibers from a plurality of detecting units or a bundle of signal wires delivering signals from the detecting units to a control system causes a problem about size reduction or handling of the bundles, the detecting units must be adjusted individually, and works such as a rising adjustment work or adjustment work at a changing time of an installation place of the detecting units are complicated.    Patent Literature 1: Japanese Patent No. 2874020